AUTO 4X4

[X24]

I am curious to know exactly how the auto 4X4 works. I know that it puts power to the front wheels when the rears start to slip. Is there always power at the front wheels? If I am cruising down the highway are the fronts being powered or are they just along for the ride? Anyway to disengage the auto 4X4? I dont really like it (I can't have fun). Also, when I put it into 4X4 HI is it in 4X4 right away or do i have to move a little bit for it to catch? Do I need to back up when I turn it off like I did in my 93? I know the entire system is different but im not sure how it works. Anything that needs to be maintained in the 4X4 system? I use it probably once a month even if I dont need to just to keep things working. I had many problems in my 93 because the person I bought it from didnt use the 4X4. Everything was frozen and rusted. Thanks.

 

[SWLathrop]

When driving in the "AUTO" mode on a dry road, 96% of the torque is sent to the rear wheels while the remaining 4% is sent to the front. When placed into "4WD HIGH", it is a 50/50 torque split with no delay. "4WD HIGH" may be engaged at any speed up to 55MPH per Ford. I have driven my 97 Sport at 65MPH in "4WD HIGH" for miles with no adverse problems or vibrations. No need to change directions for disengagment as you will go back to the 96/4 split when switched back to the "AUTO" position. As far as disengaging the "AUTO" capability, yes you can (with the use of a toggle switch). However, it will set a code and you will have 4x4 light flashing until reconnected(the toggle switch again).

 

[93Ranger]

Auto 4x4 works like this:

a speed sensor in every wheel. the info is sent to the computer, and it is processed.

if one wheel spins faster than the others, torque is removed from the wheels and sent to the other wheels.

i.e. your back right tire is spinning faster than your front. then torque is sent to the front wheels, and taken off of the back wheels.

it's not like this on BMW's though,

normally you would expect an Open diff to get worse traction than a LS or locker, but with the BMW, it uses the open diff to its advantage.

on the X5, what happens is, that the speed sensors recognize wheel spin, and apply the brake to just that wheel. that'll cause the other wheel to grab, and not slip. one wheel could effectively pull the whole car off a patch of ice.

but the system doesn't lock the brake, that would defeat the purpose. it lightly applies it, and does so intermitently, a sequence of light on, light off.

now we all know that an ARB air locker up front and in the back is just what you need to cure all your traction blues.

 

[X24]

if i were to lift the entire truck up in the air and put it in gear, would all the tires start moving?

SWLathrop... how do i go about putting in a toggle switch on the auto 4X4?

 

[Robert]

Originally posted by 93Ranger
Auto 4x4 works like this:

a speed sensor in every wheel. the info is sent to the computer, and it is processed.

if one wheel spins faster than the others, torque is removed from the wheels and sent to the other wheels.

i.e. your back right tire is spinning faster than your front. then torque is sent to the front wheels, and taken off of the back wheels.

Slight correction. There are only two speed sensors for the Control Trac, not one at each wheel. The two speed sensors monitor the rotation speed of the front and rear driveshafts, not the wheels. If the rear driveshaft turns faster than the front driveshaft, the power is diverted to the front driveshaft until they turn the same speed again.

 

[Jim F]

SWLathrop, there's one point you did not mention. The Auto 4X4 system disengages once 35mph is reached. I heard it was 95/5 percent split but maybe it is 96/4. Once the vehicle speed exceeds 35mph, the split is removed and there is 100% to the rear and the front is just spinning with some drag due to the gears that they are turning in the front differential. The front wheels are directly connected to the front differential with CV joints so at highway speed both front CV joints are spinning. The front driveshaft is at the same speed as the rear due to the same gear ratio front and rear. This is one of the reasons the system can be engaged up to 55mph.

When I'm pulling a steep hill on dry pavement, I get a vibration in the steering wheel until I have exceeded 35mph. The more I give it gas, the stronger the vibration. I understand that the 96/4 split is changed under heavy acceleration regardless of wheel slip. During this steep hill climb, I am giving it more throttle and causing the split to change and transfering more power to the front wheels causing them to slip slightly causing the vibration. The funny thing is I don't see and wear on the front tires supporting this theory. Heavy accleration on level ground has no noticable vibration. Has anyone else experience this same vibration?

 

[SWLathrop]

I quoted the operation specs right from the 97' source book. As far as any vibrations, I get none under hard acceleration. I have several hills to climb going to and from work. The only vibration I get is after running the thru-way at 75+MPH and stopping to pay my toll. Then I get a vibration the disappears after about 3-5 miles. As far as the power split being removed when reaching 35MPH, I don't believe mine does. This is based on the fact that when I get on the throttle (not real hard) at any speed, I'll get a slight pull to the right or left. Then again, this could be caused by the T-case reapplying torque to the front axle.

To 98FordX24: As far as disconnecting the "AUTO" capabilities, I have not done this. However, I believe that one needs to put a toggle switch between the "AUTO" switch position and the GEM Controller to break open that circuit.

 

[X24]

Maybe I'm better off not messing with it.

 

[rustytr]

Hmm, I didn't know about the torque split, I learned sumptin new mom...